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Role for habitats and biodiversity
Trunks and branches provide shelter, breeding grounds and hunting sites for invertebrates, fish and amphibians. They create varied microâeuroshabitats (deep pools, calm zones, fast-flowing water veins) that increase the number of species and the quantity of fauna present.
Water quality and sediment dynamics
Deadwood traps sediment, organic matter and some particulate pollutants, helping to limit turbidity and filter water naturally. In fact, by diversifying current speeds, it favors areas where materials are deposited and reclaimed, thus maintaining a more natural and stable light.
Bank protection, flooding and carbon
In addition, by slowing down the flow, dead wood limits the erosion of certain banks and dissipates flood energy, contributing to the local attenuation of peak flows. Trunks store carbon over long periods: by decomposing slowly, they contribute to the carbon cycle and the sink role of aquatic ecosystems.
Sensitive species and river resilience
Many endangered species (grayling fish, salmonid juveniles, sculpin, crayfish, specialized aquatic insects) depend on submerged woodlands to hide, reproduce or feed. After floods, droughts or fires, dead wood serves as a â??skeletonâ? for recolonization: as a support for biofilm, plants, macroaerosinvertebrates and a refuge for wildlife, it accelerates the regeneration of the watercourse.
Management: leave, secure, explain
In most natural stretches, retaining deadwood is therefore beneficial, and even desirable. Only in situations where safety is at stake (bridges, structures, populated areas) is it justified to remove or reposition it, while ensuring that sufficient woody structures are retained elsewhere to maintain ecological functions.
